Browse Prior Art Database

Optimization of Logical Drive Parameters based on Drive Size

IP.com Disclosure Number: IPCOM000115848D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Bolt, MM: AUTHOR [+5]

Abstract

Disclosed is a method extending the CBIOS interface for fixed disks in a personal computer to allow the use of such devices storing up to 7.81 (GB) Gigabytes. Without using this method, fixed disks larger than 1 GB cannot be used in IBM PC and PS/2* systems due to CBIOS interface limitations and Disk Operating System (DOS) implementation design points.

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Optimization of Logical Drive Parameters based on Drive Size

      Disclosed is a method extending the CBIOS interface for fixed
disks in a personal computer to allow the use of such devices storing
up to 7.81 (GB) Gigabytes.  Without using this method, fixed disks
larger than 1 GB cannot be used in IBM PC and PS/2* systems due to
CBIOS interface limitations and Disk Operating System (DOS)
implementation design points.

      In accordance with this method, during Power-On-Self-Test
(POST), the POST code invokes a Small Computer System Interface
(SCSI) interface to a fixed disk in the system to determine the size
of the fixed disk.  The POST code then sets a flag in memory for the
SCSI Basic Input Output System (BIOS) to inspect on each BIOS call.
This flag is a set of bits encoding a size range within which the
actual drive size falls.  After this, on every operation dealing with
the logical size of the disk, the SCSI BIOS inspects the flag and
points to the logical parameter table for the drive size range.

      This method, being completely compatible for use with drives
having a capacity less than 1 GB, is transparent to users of DOS and
smaller capacity fixed disks.  The parameters are still optimized for
these drives, being identical to the parameters conventionally used.

      This method furthermore provides for the coexistence of the
drives having capacities less than, and more than, 1 GB.  A large
drive can be added to the system having a sm...